Abstract: A device is disclosed for the selective clamping of an axially moveable or rotatable cylindrical shaft. The device disclosed may be either of a spring actuated-pressure release or a pressure actuated spring release embodiment. A clamping sleeve is located coaxially surrounding the cylindrical shaft to be immobilized. The clamping sleeve is separated into clamping elements at one end by longitudinal slots in the generally cylindrical sleeve. An actuating element is also arranged coaxially to the cylindrical body and the clamping sleeve and is mounted exterior to the clamping sleeve. The clamping elements are located radially inwardly from the actuating element and are separated therefrom by a series of bearings. The bearings engage the actuating element and the clamping elements through matched sets of inclined ramp elements. Each clamping element is provided with a set of bearings and ramp elements.